Talk:Frame-dragging/Archive 1

document ancestry
An early version of this article was adapted from public domain material from http://science.msfc.nasa.gov/newhome/headlines/ast06nov97_1.htm 

This currently is mostly press-release journalese, but it will do for now to stimulate the development of a proper article in due course. -- The Anome 23:36, 13 Apr 2004 (UTC)

linked from slashdot
http://science.slashdot.org/science/04/04/19/232237.shtml?tid=134&tid=160 -- Finlay McWalter | Talk 11:53, 20 Apr 2004 (UTC) http://science.slashdot.org/science/05/11/19/077220.shtml?tid=236&tid=14 -- 19 Nov 2005

Removed comment
I removed this comment about Gravity Probe B:


 * Note: The experiment was completed supporting frame-dragging.

as I can't find any evidence of a preliminary result from the Gravity Probe B team to back this up. -- The Anome 13:02, 24 Oct 2004 (UTC)

frame dragging due to simple acceleration
The principle of relativity, applied to acceleration and rotation, requires that both effects distort spacetime (basically, if an object is made to feel gee-forces, there's a back-reaction on the shape of the region). So, if you forcibly-accelerate a mass, you create a distortion that tends to pull other nearby objects along with it (as, when you rotate a mass, it tends to pull other nearby objects around with it).

This page only seemed to mention the "rotational" effect (which is probably the better known of the two), so I took the liberty of squeezing a few words into the intro to acknowledge the existence of the the "acceleration" version. ErkDemon 00:57, 17 July 2005 (UTC)

Accelerational frame-dragging and warp fields
PS: if you forcibly accelerate a hollow spherical mass, the gravitomagnetic field created inside it looks awfully like an Alcubierre warpdrive field. ErkDemon 00:56, 17 July 2005 (UTC)

Recent controversy
This article has recently been subject to some highly POV editing between two competing points of view, with accusations of censorship and other name-calling in the other article text. See, for example, recent edits by User:87.17.229.141, and various other Italian IP addresses beginning with 87, some of the most recent of which accuse other editors of censorship, with accusations that they are mentally ill (see this edit and this edit). It has also grown a rather large bibliography, yet currently lacks any specific supporting citations or attributions for any of the controversial opinions in the article.

Since most of the content of this article seems to be the disputed content, I have now removed all the disputed content, reducing the article to a very brief but (I hope) uncontentious stub. This article now needs to be rebuilt, with serious attention to WP:NPOV and WP:CITE, to bring it up to date with current scientific knowledge, explicitly mentioning which areas are the subject of current scientific controversy. -- The Anome 12:27, 29 January 2007 (UTC)

OK, I've made a start on this: the LAGEOS stuff is now a small part of the article, and just references the supporting references given in the earlier version of the article, without going into great detail: this article is about frame-dragging, not just this particular experiment. -- The Anome 13:23, 29 January 2007 (UTC)


 * (Next time), can you copy the disputed content to the talk page? This makes it more readily visible, and allows it to be discussed, point by point. linas 01:13, 30 January 2007 (UTC)

The disputed sections
The edit war appears mostly to be over the following text, and the papers listed in the references. The issue appears to be Iorio's et. al's criticism of Ciufolini et al's re-analysis of the LAGEOS data. As just a very small sample of what has being going on, in this edit various mentions to papers by L. Iorio disappear, and in this edit, the disputed text is restored, along with the addition of a large number of papers by L. Iorio.

The disputed text and references are batted to and fro, over and over again, with no attempt at a neutral point of view by representing both sides' views, and the tone is far too technical for an encyclopedia article. This needs to stop, and the anonymous participants in the edit war need to collaborate on the article. If this detailed level of scientific discussion is to be incorporated in the article, it should first be introduced with an introduction that will allow it to be understood by readers not already familiar with the discussion.

BEGIN DISPUTED TEXT


 * Another consequence of the gravitomagnetic field of a central rotating body is the so-called Lense-Thirring effect (Lense and Thirring 1918). It consists of small secular precessions of the longitude of the ascending node $$\Omega$$ and the argument of pericenter $$\omega$$ of the path of a test mass freely orbiting the spinning main body. de Sitter (1916) worked out the gravitomagnetic pericentre precession in the particular case of equatorial orbits. Lense and Thirring (1918) originally proposed to use the natural satellites of the gaseous giant planets of the Solar System, especially Jupiter, to detect their effect, but such a possibility is not yet viable today (Iorio and Lainey 2005). In regard to the Earth's gravitational field, Cugusi and Proverbio (1978) proposed for the first time to use the LAGEOS satellite, just launched at that time, along with the other existing terrestrial artifical satellites to measure the Lense-Thirring effect with the Satellite Laser Ranging (SLR) technique. Later, Ciufolini (1986) proposed to built and launch a new SLR satellite of LAGEOS-type in supplementary orbital configuration with respect to LAGEOS, but, to date, no effective plans have yet been approved to implement such a proposal. For the nodes of the LAGEOS and LAGEOS II satellites the Lense-Thirring node rates amount to ~30 milliarcseconds per year (ms/$${yr}$$ or ms $${yr}^{-1}$$). Such tiny precessions would totally be swamped by the much larger classical precessions induced by the even zonal harmonic coefficients $$J_{\ell},\ \ell=2,4,6...$$ of the multipolar expansion of the Newtonian part of the terrestrial gravitational potential. Even the most recent Earth gravity models from the dedicated CHAMP and GRACE missions would not allow to know the even zonal harmonics to a sufficiently high degree of accuracy in order to extract the Lense-Thirring effect from the analysis of the node of only one satellite.


 * Ciufolini (1996) proposed to overcome this problem by suitably combining the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II in order to cancel out all the static and time-dependent perturbations due to the first two even zonal harmonics $$J_2,\ J_4$$. Various analyses with the pre-CHAMP/GRACE JGM-3 and EGM96 Earth gravity models were performed by Ciufolini et al. over observational time spans of some years (Ciufolini et al. 1996; 1997; 1998). The claimed total accuracies were in the range of 20-25% (Ciufolini 2004). However, subsequent analyses by Ries et al. (2003a; 2003b) and Iorio (2003) showed that such estimates are largely optimistic. Indeed, a more conservative and realistic evaluation of the impact of the uncancelled even zonal harmonics $$J_6,\ J_8,\ J_{10},...$$, according to the adopted EGM96 model, yield a systematic error of about 80% at 1-sigma level. Moreover, also the systematic error due to the non-gravitational perturbations mainly affecting the perigee of LAGEOS II was underestimated.


 * The opportunities offered by the new generation of Earth gravity models from CHAMP and, especially, GRACE allowed to discard the perigee of LAGEOS II, as pointed out by Ries et al. (2003a; 2003b). In 2003 Iorio, following the strategy put forth by Ciufolini (1996), put explicitly forth a suitable linear combination of the nodes of LAGEOS and LAGEOS II which cancels out the first even zonal harmonic $$J_2$$ (Iorio and Morea 2004). Such an observable was used by Ciufolini and Pavlis in a test performed with the 2nd generation GRACE-only EIGEN-GRACE02S Earth gravity model over a time span of 11 years (Ciufolini and Pavlis 2004). The claimed total error budget is 5% at 1-sigma level and 10% at 3-sigma level. However, Iorio (2005a; 2005b; 2006a; 2006b) criticized such results because of the neglected impact of the secular variations of the uncancelled even zonal harmonics $$\dot J_4,\ \dot J_6$$ which would amount to about 13%. This would yield a total error of $$\sim$$ 20% at 1-sigma level. Moreover, the latest CHAMP/GRACE-based Earth gravity models do not yet allow for a model-independent measurement. Indeed, the systematic error due to the static part of the even zonal harmonics amounts to 4% for EIGEN-GRACE02S, 6% for EIGEN-CG01C and 9% for GGM02S at 1-sigma level. Another potential source of additional systematic bias may be represented by the cross-coupling among  $$J_2$$ and the residuals of the inclination $$\delta i$$, as pointed out by Iorio (2006b). Other papers on such a long-lasting, sometimes harsh, controversy are (Ciufolini and Pavlis 2005; Lucchesi 2005).


 * By the way, such a controversial test has recently been superseded by an unexpected result in the gravitational field of Mars. Indeed, by suitably interpreting the RMS orbit overlap differences of the out-of-plane portion (Konopliv et al. 2006) of the orbit of the Mars Global Surveyor (MGS) spacecraft which orbited the red planet along a nearly polar orbit until November 2006, Iorio (2006c) reported a 6% measurement, on average, of the Lense-Thirring effect. A further analysis (Iorio 2007a), based on a more detailed calculation, extended time span and error analysis, has pushed the precision level of such a test below the 1% level. A lively debate about such finding can be found in (Krogh 2007; Iorio 2007b; Sindoni et al. 2007; Iorio 2007c).


 * Other preliminary tests of the Lense-Thirring effect induced by the Sun's gravitomagnetic field on the orbital motions of the inner planets of the Solar System can be found in (Iorio 2005c). The predictions of general relativity for the Lense-Thirring perihelion precessions are, in fact, in agreement with the latest determinations of the extra-perihelion advances of the inner planets (Pitjeva 2005a) obtained with the EPM2004 ephemerides (Pitjeva 2005b), but the errors are still large.

END DISPUTED TEXT

-- The Anome 14:55, 4 February 2007 (UTC)

Mathematical treatment of frame-dragging
I've now added an empty section to the article, tagged with a request for expansion. Perhaps we could first have a mathematical treatment of what frame-dragging actually is, before we have detailed arguments about whether or not one particular group have observed it? -- The Anome 15:40, 4 February 2007 (UTC)


 * Nope. Apparently we can't -- one of the previous IP editors has just banged the disputed material right back in by reverting to a previous version of the article, removing the in-text cites, and any other work on the article. (see diff) Since they react to any editing that touches their text by reverting the article in its entirety, I'll try another approach.


 * I've now tagged the disputed text with NPOV, re-added the in-text citations to Lense, Thirring and Einstein, and re-added the empty mathematical treatment section, together with an expand tag. Let's see if this helps. -- The Anome 09:33, 5 February 2007 (UTC)

Semi-protecting
The combatting IP editors are at it again: see, for example,. Wikipedia is not a venue for argumentation. I've removed the endlessly-edited experimental observation section for now, semi-protected the article for two weeks (with a note that disputes should be discussed here), and will wait to see whether they can be persuaded to create accounts and/or discuss any changes here. -- The Anome 10:53, 5 February 2007 (UTC)

To the anonymous editors of this article
This article is primarily for discussion of frame-dragging, not disputes over interpretations of particular experiments. In particular, it is not a venue for name-calling, or for communication between editors. If you wish to discuss amendments to the article, please do so here: this page is the correct place to discuss changes to the article.

Please, before you go any further:
 * read the neutral point of view policy
 * read the civility policy
 * consider adding a detailed treatment of the predictions of frame-dragging in the theory of general relativity, before you start discussing experimental observations: without first having an understanding of what is predicted by theory, other readers cannot begin to understand the details of any analysis of experimental observations as tests of the hypothesis of frame-dragging.

-- The Anome 10:58, 5 February 2007 (UTC)

Lose discussion of SR from the intro section?
The article's intro says (in part):


 * "More familiar and already-proven effects of special relativity include the equivalence of mass and energy (as seen in matter-antimatter reactions), and the Lorentz transformations which make objects near lightspeed seem to grow shorter and heavier from the point of view of an outside observer. 

It's not a bad sentence, but it doesn't seem to have anything obvious to do with frame-dragging. Perhaps it strayed in from another article?

The "frame-dragging" effect in question happens under general relativity, and doesn't exist under special relativity. Frame-dragging involves curved spacetime; special relativity depends on flat spacetime. Frame dragging is a gravitomagnetic effect that describes how the motion of a body warps lightbeam geometry; special relativity depends for its internal consistency on the idea that we know that the motion of bodies has ==zero effect== on the propagation of light.

Does anyone have any objection to the quiet removal of this sentence? I understand that sometimes some background context or historical context for an article can sometimes be valuable, but in this case, special relativity isn't the correct context (or even _a_ valid context) for the effect being described. SR may have some relevance as a building block for Einstein's general theory, but for this topic it seems to be an irrelevant building block. Frame dragging is a consequence of the general application of the principle of relativity to noninertial motion, it isn't inhertited from the the "SR" side of GR1915's family tree. SR doesn't have a lot to say on the subject, since it is partly founded on the assumption that these sorts of complicating effects don't exist ... anything that it did say on the subject would tend to be negative.

Delete sentence? ErkDemon 20:40, 5 February 2007 (UTC)


 * Done. I saw less use for it than you did.  I also updated the description of rotation frame dragging, and am seriously considering removing the "velocity frame dragging" part.  (I don't see that this article needs to include controversial items at this stage.) —The preceding unsigned comment was added by Ems57fcva (talk • contribs) 21:50, 5 February 2007 (UTC).
 * okey-doke ErkDemon 02:02, 26 February 2007 (UTC)

Recent edits (April 2007)
We seem to be dealing with two hard-nosed editors here. First there is an anon who keeps insisting on doing a cut-and-paste from an published work into this article. This is wholely improper and the publisher owns the copyright. Unless it is explicitly released to Wikipedia under the GFDL license, it cannot appear here per WP:COPY. Even then, the text is unencyclopedic and its embedded references are unusable. It really cannot be in the article.

Also, this anon is now under a WP:3RR warning. I encourage people to report it if the offending text appears again soon and 3RR is violated.

Then there are the refuting edits by Gravitom. These violate WP:NPOV and as a critique of material placed in the article belong over here on this discussion page. Gravitom - You are free to help revert the offending entry away. That would be much more helpful than fighting fire with fire.

Do note that if this business keeps up, I will request protection for this article. --EMS | Talk 06:30, 15 April 2007 (UTC)

Semi protection
Lacking any willingness to discuss concerns here on the part of either editor, semi-protection is being utilized to prevent them from editing this article at this time. If either editor wishes to make a case for their contribution, they may feel free to do it here. --EMS | Talk 18:12, 15 April 2007 (UTC)
 * The same material was once again re-added. The account is used solely to edit this article. Is this a blockable-on-sight offense? Maury 20:45, 15 April 2007 (UTC)
 * Looking over the history, it appears this user has been using a variety of anon IP's and several registered accounts. If I am reading the history correctly, which isn't always easy, the same material has now been added by a huge list of anon accounts, and then when s-protect was added, the absolutely new user Pasquino who's only edit was this article. We are clearly dealing with a single editor, and all of these accounts need to be blocked ASAP. I'm not sure what the procedure for this is, however. Maury 20:58, 15 April 2007 (UTC)


 * I have reported the recent incidents as a WP:3RR violation on the Adminiatrator's noticeboard for such things. (There is a link to it at the top of WP:3RR.)  BTW - This is NOT a new account:  The previous edits were in December.  Had this been a new user, the semi-protection would have stopped him cold.  The other anon is stuck for the moment, as his account is only two days old.  Hopefully the current actions will end this, at least for now. --EMS | Talk 21:05, 15 April 2007 (UTC)

By Gravitom
There is a substantial difference between the two fighting editors: while one of them has systematically removed in the past all the references of a researcher in particular criticizing some aspects of the LAGEOS tests or discussing other tests, or, in quoting with great emphasis and bold characters some unpublished preprints againts such a researcher has systematically neglected to cite the preprints in which the criticized researcher replied, the other editor never did actions like that, quoting always all the relevant works of other researchers in this field. Thus, it is a shame that this article has been protected in a version which reflects the highly unfair behavior of the dishonest editor: again, all other references disappeared, nothing about the other works, etc.--Gravitom 12:58, 16 April 2007 (UTC)


 * Gravitom - I am working on getting the "dishonest editor" blocked and into the same boat as you are now in. The really frustrating thing about you is that you keep acting like the way to fix the problems introduced by the other editor is to comment on this edits.  The article space is not for commentary! That is what this discussion page is for.  There is a way to revert to a previous version here.  See WP:REVERT.  That is far prefereable that degrading an article further.


 * If there are changes that you would like to see in the article once the proper baseline is reestablished, please discuss them here. This atricle is in need of work, but by that I mean work to improve the overall content and accessibility of the article.  This business of adding bad material on top of bad material has to stop. --EMS | Talk 16:39, 16 April 2007 (UTC)


 * As you can see, Pasquino is another identity of the dishonest editor which, again, continues his action. Why he can edit again and again, and me not? He is a new user as me! His section is a cut-and-paste of several of his papers-its style is unmistakable: who can have doubts about the identity of such an italian guy?-I would add the following addition to a reference by Iorio gr-qc/0507041. From arXiv it turns out that such a paper is at press in Planet. Space Sci. Moreover, it should be added a couple of sentences about the failure of GP-B. Indeed, the present-day accuracy amounts to more than 150% of the Schiff precession and they explicitly claim that their goal, to be reached hopefully within December 2007, is 13%. A disaster with respect to the 1% or better claimed during the last 45 years! --Gravitom 22:17, 16 April 2007 (UTC)


 * You complaint is more than acknowledged, and you have my apologies that Pasquino has not been stopped. I do not know why the admins ignored the 3RR violation.  As for the account:  It is NOT new.  It was created last December before the article got fully protected back then, as had been dormant.  Hopefully, the shoe will be on the other foot soon:  You will be able to edit once your account is four days old.  In the meantime, if Pasquino puts in his edits again, I can get him blocked for vanadalizing after a final warning.  I also have brought this situation to the attention of an admin whom I hope will help.


 * In the meantime, I advise you to read WP:NPOV, and WP:ATT. Even if you are correct about the magnitudes of the effects as measured by Gravity Probe B being too large, any statements that you make have to be attributable to reliable sources. They cannot represent your own personal bellyaching on the topic.  Instead they need to reflect the concerns of the relevant part of the scientific community or of a notable minority withing it. --EMS | Talk 20:55, 16 April 2007 (UTC)

Pasquino has been blocked. Any further reverts by that account, or any other that appears similar like the many anon's, will result in an immediate perma-block (actually I was going to do this earlier, but didn't get around to it). Can someone post an URL to the copyvio in the meantime?

And to answer your question Gravitom, it's quite simple... breaking the rules doesn't stop the other guy from being a jerk. The wheels of justice may turn slowly, but they do turn. Patients is a virtue.

Maury 21:20, 16 April 2007 (UTC)

Oh, yes, patience..It is years that I have to do with that psycopathic, megalomaniac, deeply dishonest poor man....By the way, the source of my claims about GP-B flop is its official website itself. The fact that they expected 1% or better is almost everywhere, including the reference correctly citesd in some of previous edits. --Gravitom 23:29, 16 April 2007 (UTC)


 * First of all, I would also appreciate it if you could point us to the source of Paquino's edit. I would be nice to document the copyright violation.
 * Secondly, if there is some text that you would like put in the article ASAP, then please place it here. We will discuss it as needed and then put it up for you if it is appropriate to do so. --EMS | Talk 21:39, 16 April 2007 (UTC)

The account in now perma-blocked. After looking over the relevant material it is clear that abusive sockpuppetry is a perma-block offense. This took me a while to track down and convince myself, and really, having this work on my part belittled so lightly is just a little bit insulting. Maury 21:59, 16 April 2007 (UTC)


 * ??? If I have belittled you you have mu apologies. The above was directed to Gravitom as he seems to know who Pasquino is and where the material in question came from.  If that is not it, then please feel free to enlighten me on my talk page.  (If this involved the tag I changed, I was looking at contracdictory tags between the user page the talk page, and no evidence of a perma-block in the block log.) --EMS | Talk 22:37, 16 April 2007 (UTC)

AGAIN PASQUINO!! How it is possible that he continues to edit with always the same stuff violating various Wiki rules??!!!? User:Gravitom 10:14, 18 April 2007 (UTC)


 * You should be able to edit now. Please stop complaining and start reverting.  I will see what can be done about this nuisance. --EMS | Talk 15:38, 18 April 2007 (UTC)


 * BTW - Pasquino is now blocked for a week, and the blocks will only get longer if he persists in posting that copyrighted material. --EMS | Talk 16:16, 18 April 2007 (UTC)

Diagrams requested
It would be nice to illustrate the basic effect, as well as each of the experimental configurations used to test them. I was particularly confused by the description of the "butterfly configuration". -- Beland 00:26, 21 April 2007 (UTC)

It means that if, say, LAGEOS has an inclination of 110 deg to the Earth's equator, LARES is inclined of 70 deg. See the references cited in the article. --User: Gravitom 0:51, 27 April 2007 (UTC)

Astrophysical evidence
There exist dramatic astrophysical evidence of frame dragging that should be included with this article. The most effective explanations for the properties of relativistic jets stem from the frame dragging effects of rotating black holes.Tcisco 15:40, 2 May 2007 (UTC)

The censor finally disappeared!
Nice to see that the poor man and/or his stupid servants ceased their idiotic censoring actions —Preceding unsigned comment added by 79.18.23.30 (talk) 21:13, 2 January 2008 (UTC)

Rotational frame-dragging
Please clarify: the Gravity Probe B experiment confirmed the geodetic effect - it has not yet confirmed the Lense-Thirring effect

Those two event horizons...
For the uninitiated: Is it fair to say that the outer event horizon contains a region where light cannot propagate at any speed (however slow) in the direction opposite from the hole's rotation, while the inner event horizon contains the region where it cannot propagate at any speed outward from the center of the hole? Wnt (talk) 15:25, 18 March 2008 (UTC)

WARNING! Again censoring actions! Please, moderators act immediately!
Giampiero Sindoni has recently removed an entire paragraph containing detailed and referenced criticisms to the ongoing LARES mission. As in a previous editing battle, again references by a researcher, L. Iorio, have been censored. Actions like those must be immediately blocked to prevent another editing war. —Preceding unsigned comment added by 87.16.73.249 (talk) 00:46, 13 April 2008 (UTC)


 * 87.16.73.249 please do not insert rants against other editors in the article. The article is for people to read, this page is for the discussion.  You also should not conduct technical arguments in the article, Wikipedia is an encyclopedia, not a physics journal.  Sp in ni  ng  Spark  09:00, 13 April 2008 (UTC)


 * Spinningspark, it's ok concerning the excessive technicality of some posts, but it is a fact that Giampiero Sindoni cancelled all the paragraph in which doubts concerning the successful outcome of the LARES mission, with appropriate references, were contained. It should be obvious that THIS is precisely a really childish behaviour! —Preceding unsigned comment added by 79.12.79.57 (talk) 09:39, 13 April 2008 (UTC)
 * It may be wrong for Sindoni to do that, but you must not attack him for it in the article. That is even more wrong.  Here on the talk page is the place to discuss any misbehaviour.  Sp in ni  ng  Spark  10:35, 13 April 2008 (UTC)


 * I noted that Giampiero Sindoni is member of the LARES collaboration: this is how they intend to defend their claims? L. Iorio always put forth quantitative arguments, with numbers, plots and reasonongs which can be openly discussed by everyone.  —Preceding unsigned comment added by 79.12.79.57 (talk) 09:51, 13 April 2008 (UTC)
 * I deleted the personal and argumentative stuff from the article but I have left in the references to the criticism of the 1% claim. That should stay unless someone can demonstrate the references are inappropriate.  Sp in ni ng  Spark  10:35, 13 April 2008 (UTC)

Experimetal tests - Butterfly configuration
Further up the page in answer to a question Gravitom ga=ve this explanation for the butterfly effect:

It means that if, say, LAGEOS has an inclination of 110 deg to the Earth's equator, LARES is inclined of 70 deg.

Even if that were inserted in the article, it would still not make it clear (so I am not going to do it - yet). If two orbital planes are at 180o to each other, surely that is the same plane? Are the satellites in the same orbit but opposite sides? Are they counter-rotating?

The whole Experimental Tests section is dense and inpenetrable. We need to start making this section readable for our encyclopedia readers.  Sp in ni ng  Spark  09:34, 13 April 2008 (UTC)

Something wrong with units
with this formula:

\Omega = \frac{r_{s} \alpha r}{\rho^{2} \left( r^{2} + \alpha^{2} \right) + r_{s} \alpha^{2} r \sin^{2}\theta} $$ --79.111.163.130 (talk) 14:06, 3 July 2008 (UTC)


 * The c in the numerator is missing in your formula, but it seems to have been restored in the article. I amended the Kerr metric, so that everything should be consistent. Willow (talk) 06:09, 6 July 2008 (UTC)

Obscure phrase needs clarification
I edited the article to indicate that the phrase, "more mismodelled even zonal harmonics" needs clarification. It is jargon probably understandable only by experts in the field. WP is a general encyclopedia and should be understandable by any intelligent, generally educated person. Could someone knowledgeable please expand this phrase into a paragraph or two of explanation? In particular, please make clear what "zonal harmonics" are (harmonics of what periodic phenomenon? in what way are they related to zones?) and how such harmonics are mismodelled. David (talk) 13:10, 17 August 2008 (UTC)

Explanation of the terminology
If the Earth did not rotate it would be a perfect sphere. Thus, its gravitational potential as sensed by an orbiting satellite would be simply U = -GM/r; as a consequence, its path would be a Keplerian ellipse fixed in space.

In reality, the Earth experiences diurnal rotation, so that it is not a sphere but an oblate spheroid because of the centrifugal force. As a consequence, its gravitational potential is no longer equal to U = -GM/r; in order to take into account the effects of the centrifugal force it must be expanded in multipoles, i.e. it must be written as U = -GM/r(1 + J2 a2 + J4 a4 + J6 a6 + ...) where J2, J4, J6... are the even zonal harmonic coefficients (known also as even zonals or even zonal harmonics) of the expansion (a2, a4, a6, are other adimensional coefficients containing the latitude, the Earth's equatorial radius R and r). The even zonals JL, L = 2,4,6,... can be written as JL = JL0 + JL(t) where JL0 is a time-independent part; JL(t) include secular (i.e. cumulative), seasonal and sinusoidal temporal variations.

It turns out that the motion of a satellite is affected by the static part JL0, L = 2,4,6,8... of the even zonals in various ways; in particular, the orbital plane is no more fixed in space, as it would be if the Earth was spherical, but changes its orientation in a steadily way, i.e. it is a cumulative effect qualitatively similar to that induced by the Lense-Thirring effect, but quantitatively much larger than it.

Recently published works on LARES
Some recently published references on LARES have been added in the article page. Let us hope that the well known italian megalomaniac, pathetic and paranoid censor and/or his monkeys and stupid servants will not delete them. Let us see.. —Preceding unsigned comment added by 79.50.20.83 (talk) 14:34, 13 December 2008 (UTC)


 * Please stop this incivility. Also, get an account, otherwise it will make people think you are using multiple IP addresses to hide your long term rudeness from us.  Sp in ni  ng  Spark  02:41, 14 December 2008 (UTC)


 * As a user of this encyclopedia I must say that I felt myself damaged by the highly unfair actions of those (I do not speculate about the identity of such people) guys who in the recent past sistematically removed the references by one and the same researcher in particular. It is against any scientific ethic and prevents other users to make an own informed judgement on such a difficult and intricate topic. I think this is the main point. Undoubtedly, certain tones are too rude and unappropriate here, but I cannot blame too much those who use them. By the way, now all the references are in place and we hope they will remain there. —Preceding unsigned comment added by 79.46.75.207 (talk) 09:35, 14 December 2008 (UTC)


 * There seems to be a misconception here that Wikipedia is a directory of research papers. It is not, Wikipedia is an encyclopedia.  The purpose of an encyclopedia article is to give the reader a clear picture of the subject.  The purpose of the references is for verification of the facts stated in the article, nothing more.  It is not necessary to list every paper ever published (or about to be published), nor is Wikipedia the right place to conduct disputes about the validity of the experiments.  The whole section on experimental tests is next to unreadable.  You would help Wikipedia far more by making this section more understandable to the general reader than by continuing the argument over who is more right on the accuracy of the measurements.  Understanding what is being done is the first need of the article, the accuracy of the measurements is a rather obscure side issue to most readers.  To help you, here is a list of some of the things I think are needed;
 * Divide the section with sub-headings describing each experiment or proposed experiment separately
 * Clear description of the satellite configurations being used in each experiment; better still, provide diagrams. If you are not able or have time to produce professional diagrams, then post a pencil sketch on this talk page so that someone else can work on it.  Requests for an explanation of the butterfly configuration have been made several times but with no helpful response.
 * Clear explanations of the jargon, eg "butterfly configuration" and "zonal harmonics", if necessary in a side-box or even separate article.
 *  Sp in ni ng  Spark  13:44, 14 December 2008 (UTC)

Assessment comment
Substituted at 14:48, 1 May 2016 (UTC)